DialogFragment的基本用法

1. 创建DialogFragment

public class DialogA extends DialogFragment implements DialogInterface.OnClickListener { @Override public Dialog onCreateDialog(Bundle savedInstanceState) { AlertDialog.Builder builder = new AlertDialog.Builder(getActivity()); builder.setMessage(R.string.dialoga_title) .setPositiveButton(R.string.ok, this) .setNegativeButton(R.string.cancel, this); return builder.create(); } @Override public void onClick(DialogInterface dialog, int id) { switch(id) { case AlertDialog.BUTTON_NEGATIVE: Toast.makeText(getActivity(), "Negative", Toast.LENGTH_SHORT).show(); break; case AlertDialog.BUTTON_POSITIVE: Toast.makeText(getActivity(), "Positive", Toast.LENGTH_SHORT).show(); break; default: break; } } }

说明：自定义一个DialogFragment，并重写它的onCreateDialog()方法。

2. 调用该DialogFragment

下面是在FragmentActivity中调用该DialogFragment对话框。

public class DialogTest extends FragmentActivity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); showDialog(); } private void showDialog() { FragmentManager fm = getSupportFragmentManager(); DialogA dialoga = new DialogA(); dialoga.show(fm, "fragmenta"); } }

自定义DialogFragment布局

下面介绍自定义DialogFragment的布局的方法

点击查看：自定义DialogFragment布局的完整代码

1. 设置布局文件

<"1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" > <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="@string/dialoga_intro" /> <ImageView android:id="@+id/image" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/ic_action_video" /> </LinearLayout>

2. 使用布局

public class DialogA extends DialogFragment implements DialogInterface.OnClickListener { @Override public Dialog onCreateDialog(Bundle savedInstanceState) { AlertDialog.Builder builder = new AlertDialog.Builder(getActivity()); LayoutInflater inflater = getActivity().getLayoutInflater(); builder.setView(inflater.inflate(R.layout.dialoga, null)) .setMessage(R.string.dialoga_title) .setPositiveButton(R.string.ok, this) .setNegativeButton(R.string.cancel, this); return builder.create(); } @Override public void onClick(DialogInterface dialog, int id) { switch(id) { case AlertDialog.BUTTON_NEGATIVE: Toast.makeText(getActivity(), "Negative", Toast.LENGTH_SHORT).show(); break; case AlertDialog.BUTTON_POSITIVE: Toast.makeText(getActivity(), "Positive", Toast.LENGTH_SHORT).show(); break; default: break; } } }

DialogFragment和Activity的交互

下面介绍自定义DialogFragment和Activity交互的方法

点击查看：DialogFragment和Activity交互的完整代码

1. 定义通信接口

在DialogFragment中定义它们之间的通信接口。

public interface NoticeDialogListener { public void onDialogPositiveClick(DialogFragment dialog); public void onDialogNegativeClick(DialogFragment dialog); } // Use this instance of the interface to deliver action events NoticeDialogListener mListener; // Override the Fragment.onAttach() method to instantiate the NoticeDialogListener @Override public void onAttach(Activity activity) { super.onAttach(activity); // Verify that the host activity implements the callback interface try { // Instantiate the NoticeDialogListener so we can send events to the host mListener = (NoticeDialogListener) activity; } catch (ClassCastException e) { // The activity doesn't implement the interface, throw exception throw new ClassCastException(activity.toString() + " must implement NoticeDialogListener"); } }

2. 在DialogFragment中调用该接口

@Override public void onClick(DialogInterface dialog, int id) { switch(id) { case AlertDialog.BUTTON_POSITIVE: //Toast.makeText(getActivity(), "Negative", Toast.LENGTH_SHORT).show(); mListener.onDialogPositiveClick(DialogA.this); break; case AlertDialog.BUTTON_NEGATIVE: //Toast.makeText(getActivity(), "Positive", Toast.LENGTH_SHORT).show(); mListener.onDialogNegativeClick(DialogA.this); break; default: break; } }

3. 在Activity中实现该接口

public class DialogTest extends FragmentActivity implements DialogA.NoticeDialogListener { ... @Override public void onDialogPositiveClick(DialogFragment dialog) { Toast.makeText(this, "Positive Callback", Toast.LENGTH_SHORT).show(); } @Override public void onDialogNegativeClick(DialogFragment dialog) { Toast.makeText(this, "Negative Callback", Toast.LENGTH_SHORT).show(); } }

Dialog与DialogFragment的对比

从代码的编写角度看，Dialog使用起来要更为简单，但是Google则是推荐尽量使用DialogFragment（对于Android 3.0以下的版本，可以结合使用support包中提供的DialogFragment以及FragmentActivity）。今天试着用这两种方式来创建对话框，发现DialogFragment果然有一个非常好的特性（在手机配置变化，导致Activity需要重新创建时，例如旋屏，基于DialogFragment的对话框将会由FragmentManager自动重建，然而基于Dialog实现的对话框则没有这样的能力）。

下面是两段实例代码：

他们使用的界面都一样：（dialog.xml）

<"1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" > <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/ic_launcher" /> </LinearLayout>

1.基于Dialog实现的对话框

public class MainActivity extends Activity { private Button clk; private Dialog dialog; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); clk = (Button) findViewById(R.id.clk); dialog = new Dialog(this); dialog.setContentView(R.layout.dialog); clk.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { dialog.show(); } }); } }

当我们点击按钮时，会弹出对话框（内容为android logo），当我们旋转屏幕后，Activity重新创建，整个Activity的界面没有问题，而对话框消失了。

除此之外，其实还有一个问题，就是在logcat中会看到异常信息：Android..leaked .. window，这是因为在Activity结束之前，Android要求所有的Dialog必须要关闭。我们旋屏后，Activity会被重建，而上面的代码逻辑并没有考虑到对话框的状态以及是否已关闭。

于是将上述代码修改为：

public class MainActivity extends Activity { private Button clk; private Dialog dialog; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); clk = (Button) findViewById(R.id.clk); dialog = new Dialog(this); dialog.setContentView(R.layout.dialog); clk.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { dialog.show(); } }); //用户恢复对话框的状态 if(savedInstanceState != null && savedInstanceState.getBoolean("dialog_show")) clk.performClick(); } /** * 用于保存对话框的状态以便恢复 */ @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); if(dialog != null && dialog.isShowing()) outState.putBoolean("dialog_show", true); else outState.putBoolean("dialog_show", false); } /** * 在Activity销毁之前，确保对话框以关闭 */ @Override protected void onDestroy() { super.onDestroy(); if(dialog != null && dialog.isShowing()) dialog.dismiss(); } }

2. 基于DialogFragment的对话框

与上面的对话框使用同样的界面布局，此处仅仅展现一个简单对话框，因此只重写了onCreateView方法

public class MyDialogFragment extends DialogFragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View v = inflater.inflate(R.layout.dialog, container, false); return v; } } public class MainActivity extends FragmentActivity { private Button clk; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); clk = (Button) findViewById(R.id.clk); clk.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { MyDialogFragment mdf = new MyDialogFragment(); FragmentTransaction ft = getSupportFragmentManager().beginTransaction(); ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE); mdf.show(ft, "df"); } }); } }

这两段代码可以实现第一种方式的同样功能，此处我们并没有去关心对话框的重建，以及Activity销毁前对话框是否已关闭，这一切都是由FragmentManager来管理。

其实DialogFragment还拥有fragment的优点，即可以在一个Activity内部实现回退（因为FragmentManager会管理一个回退栈）